Providing query correlation attributes

ABSTRACT

A system, method and article of manufacture for accessing data are disclosed. In general, data access is facilitated by a query configured with a correlation criterion or criteria. The presence of the correlation criteria facilitates the introduction of additional correlation logic to be applied to conditions of the query. In general, correlation criteria are contemplated which support correlation of entities based on time, physical location and age, for example.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/285,228, filed Oct. 31, 2002 entitled “GLOBAL QUERY CORRELATIONATTRIBUTES,” now U.S. Pat. No. 7,096,217, which is herein incorporatedby reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to data processing and moreparticularly to accessing data using correlation criterion or criteria.

2. Description of the Related Art

Databases are computerized information storage and retrieval systems. Arelational database management system is a computer database managementsystem (DBMS) that uses relational techniques for storing and retrievingdata. The most prevalent type of database is the relational database, atabular database in which data is defined so that it can be reorganizedand accessed in a number of different ways.

Regardless of the particular architecture, in a DBMS, a requestingentity (e.g., an application or the operating system) demands access toa specified database by issuing a database access request. Such requestsmay include, for instance, simple catalog lookup requests ortransactions and combinations of transactions that operate to read,change and add specified records in the database. These requests aremade using high-level query languages such as the Structured QueryLanguage (SQL). Illustratively, SQL is used to make interactive queriesfor getting information from and updating a database such asInternational Business Machines' (IBM) DB2, Microsoft's SQL Server, anddatabase products from Oracle, Sybase, and Computer Associates. The term“query” denominates a set of commands for retrieving data from a storeddatabase. Queries take the form of a command language that letsprogrammers and programs select, insert, update, find out the locationof data, and so forth.

When constructing complex queries against information stored in adatabase or data warehouse, it is often desirable to correlate the dataentities being queried based on a common attribute. For example, dataentities may be correlated based on all entities or events that: (i)occurred at a given point in time or within a given time span; (ii)occurred at the same time or within a given time interval of each other;(iii) occurred at the same location which may be scoped a number ofdifferent ways (e.g., same street address, city, county, state, postalcode, or country); (iv) occurred when an individual or item in questionwas a given age or within a given age range; and (v) occurred when theage associated with all data entities in question was the same.

The typical approach to constructing such complex queries involvesaugmenting the query with additional predicates to factor in the logicfor the common correlation attribute(s) for each data entity beingqueried. Unfortunately, this approach requires a deeper understanding ofthe physical relationship of the data involved and of the particulardata entities being queried (e.g., whether the data entity supports theconcept of time, age or location). By way of example, consider a userinterested in identifying males currently 60 years of age or older whowere found to have a liver enzyme level above a certain threshold andwho underwent surgery to correct the liver abnormality. In SQL, acorresponding query may take the form of Query 1.

SQL QUERY 1 SELECT ASTValue, Diagnostics, SurgeryType  FROMDemographics, TestResults, SurgeryRecord  WHERE Gender =”M” AND YEAR (CURRENT_DATE − BirthDate) >= 60 AND ASTValue > 30 AND SurgeryType =“Liver”

Now assume the user desires to narrow the data returned to only includethose cases where the person was tested and had the surgery withinthirty days. This could be accomplished by extending the SQL Query 1with additional predicates to select test and surgery events thatoccurred within the same time span, as illustrated by Query 2.

SQL QUERY 2 SELECT ASTValue, Diagnostics, SurgeryType  FROMDemographics, TestResults, SurgeryRecord  WHERE Gender =”M” AND YEAR (CURRENT_DATE − BirthDate) >= 60 AND ASTValue > 30 AND SurgeryType =“Liver” AND  DAYS (SurgeryDate − TestDate) <= 30

In another case, the user may desire to identify individuals with thesame combination of criteria, but limiting the results to those peoplewho were between the ages of 40 and 50 when they had the test andsurgery. This would require a different set of predicates being added tothe base query, as illustrated by Query 3.

SQL QUERY 3 SELECT ASTValue, Diagnostics, SurgeryType  FROMDemographics, TestResults, SurgeryRecord  WHERE Gender =”M” AND YEAR (CURRENT_DATE − BirthDate) >= 60 AND ASTValue > 30 AND SurgeryType =“Liver” AND  YEAR (SurgeryDate − BirthDate) >= 40 AND YEAR (SurgeryDate− BirthDate) <= 50 AND YEAR (TestDate − BirthDate) > = 40 AND YEAR(TestDate − BirthDate) <= 50

The foregoing examples illustrate that, while the base query remains thesame in each case, additional predicates are added to accomplish thedesired correlation between entities examined by the query. As a result,the burden on the end-user to access the desired data is substantial.

Therefore, there is a need for a manner of implementing correlationlogic within queries.

SUMMARY OF THE INVENTION

The present invention generally is directed to a method, system andarticle of manufacture for accessing data using a correlation criterionor criteria.

One embodiment provides a method of providing attributes configured toadd query logic to a query generated from an abstract query defined byone or more logical field. The method comprises specifying which of aplurality of correlation attributes are supported for a particularlogical field; and specifying a definition for computing a value of thecorrelation attributes supported for the particular logical field.

Another embodiment provides a method of providing attributes configuredto add query logic to a query generated from an abstract query definedby one or more logical field. The method comprises for each of aplurality of logical fields, specifying which of a plurality ofcorrelation attributes are supported for a particular logical field; andfor each of a plurality of logical fields, specifying a definition forcomputing a value of the correlation attributes supported for theparticular logical field; wherein at least two of the definitions forcomputing a value of a particular correlation attribute, specified fortwo different logical fields, are different.

Another embodiment provides a method of adding query logic to a querygenerated from an abstract query defined by one or more logical field,the method comprising, for each condition of the abstract query:building an executable query contribution; determining whether theabstract query includes at least one of a plurality of correlationcriterions which applies to a logical field of the condition, whereineach of the plurality of correlation criterion have a correspondingcorrelation attribute definition for calculating a value, and wherein atleast two different corresponding correlation attribute definitions aredefined for a given correlation criterion.

Yet another embodiment provides a computer readable medium containing aprogram which, when executed, performs an operation of adding querylogic to a query generated from an abstract query defined by one or morelogical field. The operation comprises, for each condition of theabstract query: building an executable query contribution; determiningwhether the abstract query includes at least one of a plurality ofcorrelation criterions which applies to a logical field of thecondition, wherein each of the plurality of correlation criterion have acorresponding correlation attribute definition for calculating a value,and wherein at least two different corresponding correlation attributedefinitions are defined for a given correlation criterion.

Yet another embodiment provides a computer-readable medium, comprisinginformation stored thereon, the information comprising: a queryspecification comprising a plurality of logical fields for definingabstract queries; at least one correlation attribute definitionspecified for at least one of the plurality of logical fields, whereinthe correlation attribute definition comprises a name and a definitionfor calculating a value of the correlation attribute correlationattribute definition; and a runtime component executable to perform anoperation in response to receiving an abstract query issued against thedata, wherein the abstract query is defined according to the queryspecification and is configured with the at least one logical field forwhich the at least one correlation attribute definition is specified.The operation comprises calculating the correlation attribute value forthe at least one logical field.

Still another embodiment provides a computer-readable medium, comprisinginformation stored thereon, the information comprising: a queryspecification comprising a plurality of logical fields for definingabstract queries; a plurality of correlation attribute definitionsspecified for at least two of the plurality of logical fields, whereineach correlation attribute definition comprises a name and a definitionfor calculating a value of the correlation attribute correlationattribute definition; and a runtime component executable to perform anoperation in response to receiving an abstract query issued against thedata, wherein the abstract query is defined according to the queryspecification and is configured with the at least one logical field forwhich the at least one correlation attribute definition is specified.The operation comprises calculating the correlation attribute value forthe at least one logical field.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention are attained and can be understood in detail, a moreparticular description of the invention, briefly summarized above, maybe had by reference to the embodiments thereof which are illustrated inthe appended drawings.

It is to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is one embodiment of a computer system;

FIG. 2A is a logical/physical view of software components of oneembodiment of the invention;

FIG. 2B is a logical view of an abstract query;

FIG. 2C is a logical view of a data repository abstraction embodiment;

FIGS. 3A-C are a flowchart illustrating the operation of a runtimecomponent; and

FIG. 4 is a flowchart illustrating the operation of the runtimecomponent.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Introduction

The present invention generally is directed to a system, method andarticle of manufacture for accessing data. In general, data access isfacilitated by a query configured with a correlation criterion orcriteria. The presence of the correlation criteria facilitates theintroduction of additional correlation logic to be applied to conditionsof the query. In general, correlation criteria are contemplated whichsupport correlation of entities based on time, physical location andage.

In one embodiment, correlation attributes are implemented as part of alogical model of data. The logical model is referred to herein as a datarepository abstraction layer, which provides a logical view of theunderlying data repository. In this way, data is made independent of theparticular manner in which the data is physically represented. A queryabstraction layer is also provided and is based on the data repositoryabstraction layer. A runtime component performs translation of anabstract query into a form that can be used against a particularphysical data representation.

For convenience, the term “correlation” is used herein to refer to aquery criterion and an attribute defined as part of a data repositoryabstraction layer. The term “correlation” conveys one aspect of theinvention in which query logic may be applied to two or more queryconditions with respect to a common entity. However, in another aspect,query logic may also be applied to only one query condition. As will beevident from the following disclosure, an advantage is still realized bythe end-user, in that the end-user is not burdened with determining howthe entity is to be calculated. As such, “correlation” occurs between aquery condition and, for example, a particular time, location or ageattribute (versus simply correlation between two or more queryconditions). Significantly, a correlation attribute applies to the queryas a whole and will influence the data selection logic associated withall condition fields that support the particular type of correlationattribute.

One embodiment of the invention is implemented as a program product foruse with a computer system such as, for example, the computer systemshown in FIG. 1 and described below. The program(s) of the programproduct defines functions of the embodiments (including the methodsdescribed herein) and can be contained on a variety of signal-bearingmedia. Illustrative signal-bearing media include, but are not limitedto: (i) information permanently stored on non-writable storage media(e.g., read-only memory devices within a computer such as CD-ROM disksreadable by a CD-ROM drive); (ii) alterable information stored onwritable storage media (e.g., floppy disks within a diskette drive orhard-disk drive); or (iii) information conveyed to a computer by acommunications medium, such as through a computer or telephone network,including wireless communications. The latter embodiment specificallyincludes information downloaded from the Internet and other networks.Such signal-bearing media, when carrying computer-readable instructionsthat direct the functions of the present invention, representembodiments of the present invention.

In general, the routines executed to implement the embodiments of theinvention, may be part of an operating system or a specific application,component, program, module, object, or sequence of instructions. Thesoftware of the present invention typically is comprised of a multitudeof instructions that will be translated by the native computer into amachine-readable format and hence executable instructions. Also,programs are comprised of variables and data structures that eitherreside locally to the program or are found in memory or on storagedevices. In addition, various programs described hereinafter may beidentified based upon the application for which they are implemented ina specific embodiment of the invention. However, it should beappreciated that any particular nomenclature that follows is used merelyfor convenience, and thus the invention should not be limited to usesolely in any specific application identified and/or implied by suchnomenclature.

Physical View of Environment

FIG. 1 depicts a block diagram of a networked system 100 in whichembodiments of the present invention may be implemented. In general, thenetworked system 100 includes a client (e.g., user's) computer 102(three such client computers 102 are shown) and at least one server 104(one such server 104). The client computer 102 and the server computer104 are connected via a network 126. In general, the network 126 may bea local area network (LAN) and/or a wide area network (WAN). In aparticular embodiment, the network 126 is the Internet.

The client computer 102 includes a Central Processing Unit (CPU) 110connected via a bus 130 to a memory 112, storage 114, an input device116, an output device 119, and a network interface device 118. The inputdevice 116 can be any device to give input to the client computer 102.For example, a keyboard, keypad, light-pen, touch-screen, track-ball, orspeech recognition unit, audio/video player, and the like could be used.The output device 119 can be any device to give output to the user,e.g., any conventional display screen. Although shown separately fromthe input device 116, the output device 119 and input device 116 couldbe combined. For example, a display screen with an integratedtouch-screen, a display with an integrated keyboard, or a speechrecognition unit combined with a text speech converter could be used.

The network interface component 118 may be any entry/exit componentconfigured to allow network communications between the client computer102 and the server computer 104 via the network 126. For example, thenetwork interface component 118 may be a network adapter or othernetwork interface card (NIC).

Storage 114 is preferably a Direct Access Storage Device (DASD).Although it is shown as a single unit, it could be a combination offixed and/or removable storage devices, such as fixed disc drives,floppy disc drives, tape drives, removable memory cards, or opticalstorage. The memory 112 and storage 114 could be part of one virtualaddress space spanning multiple primary and secondary storage devices.

The memory 112 is preferably a random access memory sufficiently largeto hold the necessary programming and data structures of the invention.While the memory 112 is shown as a single entity, it should beunderstood that the memory 112 may in fact comprise a plurality ofmodules, and that the memory 112 may exist at multiple levels, from highspeed registers and caches to lower speed but larger DRAM chips.

Illustratively, the memory 112 contains an operating system 124.Illustrative operating systems, which may be used to advantage, includeLinux and Microsoft's Windows®. More generally, any operating systemsupporting the functions disclosed herein may be used.

The memory 112 is also shown containing a browser program 122 that, whenexecuted on CPU 110, provides support for navigating between the variousservers 104 and locating network addresses at one or more of the servers104. In one embodiment, the browser program 122 includes a web-basedGraphical User Interface (GUI), which allows the user to display HyperText Markup Language (HTML) information. More generally, however, thebrowser program 122 may be any program (preferably GUI-based) capable ofrendering the information transmitted from the server computer 104.

The server computer 104 may be physically arranged in a manner similarto the client computer 102. Accordingly, the server computer 104 isshown generally comprising a CPU 130, a memory 132, and a storage device134, coupled to one another by a bus 136. Memory 132 may be a randomaccess memory sufficiently large to hold the necessary programming anddata structures that are located on the server computer 104.

The server computer 104 is generally under the control of an operatingsystem 138 shown residing in memory 132. Examples of the operatingsystem 138 include IBM OS/400®, UNIX, Microsoft Windows®, and the like.More generally, any operating system capable of supporting the functionsdescribed herein may be used.

The memory 132 further includes one or more applications 140 and anabstract query interface 146. The applications 140 and the abstractquery interface 146 are software products comprising a plurality ofinstructions that are resident at various times in various memory andstorage devices in the computer system 100. When read and executed byone or more processors 130 in the server 104, the applications 140 andthe abstract query interface 146 cause the computer system 100 toperform the steps necessary to execute steps or elements embodying thevarious aspects of the invention. The applications 140 (and moregenerally, any requesting entity, including the operating system 138and, at the highest level, users) issue queries against a database(e.g., databases 156 ₁ . . . 156 _(N), collectively referred to asdatabase(s) 156). Illustratively, the databases 156 are shown as part ofa database management system (DBMS) in storage 134. The databases 156are representative of any collection of data regardless of theparticular physical representation. By way of illustration, thedatabases 156 may be organized according to a relational schema(accessible by SQL queries) or according to an XML schema (accessible byXML queries). However, the invention is not limited to a particularschema and contemplates extension to schemas presently unknown. As usedherein, the term “schema” generically refers to a particular arrangementof data.

In one embodiment, the queries issued by the applications 140 aredefined according to an application query specification 142 includedwith each application 140. The queries issued by the applications 140may be predefined (i.e., hard coded as part of the applications 140) ormay be generated in response to input (e.g., user input). In eithercase, the queries (referred to herein as “abstract queries”) arecomposed/executed using logical fields defined by the abstract queryinterface 146. In particular, the logical fields used in the abstractqueries are defined by a data repository abstraction component 148 ofthe abstract query interface 146. The abstract queries are executed by aruntime component 150 which first transforms the abstract queries into aform consistent with the physical representation of the data containedin the DBMS 154.

In one embodiment, the data repository abstraction component 148 isconfigured with correlation attributes 162. The correlation attributes162 may, for example, specify space and time constraints that may beplaced on a logical field to be used for defining relationships betweenconditions of a query. A correlation algorithm 151 of the runtimecomponent 150 operates to enforce the rules specified by the correlationattributes 162. To this end, the runtime component 150 may maintaintemporary data structures which include a span criteria list 170, anindividual criteria list 172, and a span field list 174.

In one embodiment, elements of a query are specified by a user through agraphical user interface (GUI). The content of the GUIs is generated bythe application(s) 140. In a particular embodiment, the GUI content ishypertext markup language (HTML) content which may be rendered on theclient computer systems 102 with the browser program 122. Accordingly,the memory 132 includes a Hypertext Transfer Protocol (http) serverprocess 152 (e.g., a web server) adapted to service requests from theclient computer 102. For example, the server process 152 may respond torequests to access the database(s) 156, which illustratively resides onthe server 104. Incoming client requests for data from a database 156invoke an application 140. When executed by the processor 130, theapplication 140 causes the server computer 104 to perform the steps orelements embodying the various aspects of the invention, includingaccessing the database(s) 156. In one embodiment, the application 140comprises a plurality of servlets configured to build GUI elements,which are then rendered by the browser program 122.

FIG. 1 is merely one hardware/software configuration for the networkedclient computer 102 and server computer 104. Embodiments of the presentinvention can apply to any comparable hardware configuration, regardlessof whether the computer systems are complicated, multi-user computingapparatus, single-user workstations, or network appliances that do nothave non-volatile storage of their own. Further, it is understood thatwhile reference is made to particular markup languages, including HTML,the invention is not limited to a particular language, standard orversion. Accordingly, persons skilled in the art will recognize that theinvention is adaptable to other markup languages as well as non-markuplanguages and that the invention is also adaptable to future changes ina particular markup language as well as to other languages presentlyunknown. Likewise, the HTTP server process 152 shown in FIG. 1 is merelyillustrative and other embodiments adapted to support any known andunknown protocols are contemplated.

Logical/Runtime View of Environment

FIGS. 2A-B show an illustrative relational view 200 of components of theinvention. The requesting entity (e.g., one of the applications 140)issues a query 202 as defined by the respective application queryspecification 142 of the requesting entity. The resulting query 202 isgenerally referred to herein as an “abstract query” because the query iscomposed according to abstract (i.e., logical) fields rather than bydirect reference to the underlying physical data entities in the DMBS154. As a result, abstract queries may be defined that are independentof the particular underlying data representation used. In oneembodiment, the application query specification 142 may include criteriaused for data selection (selection criteria 204), criteria used forcorrelating one or more (and more typically, two or more) conditions ofa query (correlation criteria 203) and an explicit specification of thefields to be returned (return data specification 206) based on theselection criteria 204.

The details of the abstract query 202 shown in FIG. 2B are shown inTable I below. By way of illustration, the abstract query 202 is definedusing XML. However, any other language may be used to advantage.

TABLE I ABSTRACT QUERY EXAMPLE 001 <QueryAbstraction> 002  <Selection>003   <Condition field=”Diagnosis” operator=”EQ” value=”Anemia”/> 004  <Condition field=”Hemoglobin” operator=”LT” value=”20” 005   relOperator=”AND”/> 006   <Correlation attribute=”Age” operator=”GT”value=”40”/> 007   <Correlation attribute=”Span(Time)” operator=”LT”value=”5” 008   relOperator=”AND”/> 009  </Selection> 010  <Results> 011  <Field name=”FirstName”/> 012   <Field name=”LastName”/> 013 </Results> 014 </QueryAbstraction>

Illustratively, the abstract query shown in Table I Includes a selectionspecification (lines 001-009) containing selection criteria and aresults specification (lines 010-014). In one embodiment, a selectioncriterion (also referred to herein as a “condition” consists of a fieldname (for a logical field), a comparison operator (=, >, <, etc) and avalue expression (what is the field being compared to). In oneembodiment, the result specification is a list of abstract fields thatare to be returned as a result of query execution. A resultspecification in the abstract query may consist of a field name and sortcriteria. Illustratively, the correlation criteria are an Agecorrelation criterion and a Span(Time) correlation criterion. Thecorrelation criteria are each applied to one or more conditions of thequery. In this example, the Age correlation criterion adds additionallogic to the individual predicates used to select particular diagnosisand test result values. The Span(Time) criterion adds additional logicto the query as a whole, in this case, selecting only those patientswhose diagnosis and test results were within 5 days of each other.

By way of comparison, the following represents the SQL querycorresponding to the abstract query of Table I.

SQL QUERY 4 SELECT f_name, I_name FROM patient WHERE  (diag = ‘Anemia’AND YEAR(diagdate−birthdate) > 40) AND  (testval < 20 ANDYEAR(testdate−birthdate) > 40) AND   (ABS(DAYS(diagdate − testdate)) <5)Note that the user is burdened with applying correlation logic to eachcondition as desired. In contrast, in the present invention, thecorrelation criteria are applied to each condition for which apredefined correlation attribute exists in the data repositoryabstraction component 148. Aspects of the data repository abstractioncomponent 148 in this regard will be described in more detail below.

In one embodiment, the correlation criteria 203, selection criteria 204,and return data specification 206 may each be specified by a user via auser interface, e.g., the browser program 122. To this end, the userinterface may include separate input fields for each of the correlationcriteria 203, selection criteria 204, and return data specification 206,whereby an abstract query 202 is composed.

The logical fields specified by the application query specification 142and used to compose the abstract query 202 are defined by the datarepository abstraction component 148. In general, the data repositoryabstraction component 148 exposes information as a set of logical fieldsthat may be used within a query (e.g., the abstract query 202) issued bythe application 140 (which may be in response to user input queryconditions) to specify criteria for data selection, criteria forcorrelation of query conditions and specify the form of result datareturned from a query operation. The logical fields are definedindependently of the underlying data representation being used in theDBMS 154, thereby allowing queries to be formed that are loosely coupledto the underlying data representation.

In general, the data repository abstraction component 148 comprises aplurality of field specifications 208 ₁, 208 ₂, . . . (six shown by wayof example), collectively referred to as the field specifications 208.Specifically, a field specification is provided for each logical fieldavailable for composition of an abstract query. In one embodiment, afield specification 208 comprises a logical field name 210 ₁, 210 ₂ . .. (collectively, field names 210) and an associated access method 212 ₁,212 ₂ . . . (collectively, access methods 212). In the illustrativeembodiment field specifications 208 also include one or more categorynames 216 ₁, 216 ₂ and 216 ₃ (collectively, category names 216). Thecategory names associate a group of logical field names. For example, inFIG. 2B the field specifications 208 ₁, and 208 ₂ are part of aDemographic category 216 ₁, the field specification 208 ₃, 208 ₄, and208 ₅ are part of a Diagnostics category 216 ₂ and the fieldspecification 208 ₆, 208 ₇, and 208 ₈ are part of a Tests category 216₂. However, the use of categories is merely representative of aparticular embodiment, and other embodiments do not utilize categories.

The access methods 212 associate (i.e., map) the logical field names toa particular physical data representation 214 ₁, 214 ₂ . . . 214 _(N) ina database (e.g., one of the databases 156). By way of illustration, twodata representations are shown in FIG. 2A, an XML data representation214 ₁ and a relational data representation 214 ₂. However, the physicaldata representation 214 _(N) indicates that any other datarepresentation, known or unknown, is contemplated.

In one embodiment, a single data repository abstraction component 148contains field specifications (with associated access methods) for twoor more physical data representations 214. In an alternative embodiment,a different single data repository abstraction component 148 is providedfor each separate physical data representation 214. In yet anotherembodiment, multiple data repository abstraction components 148 areprovided, where each data repository abstraction component 148 exposesdifferent portions of the same underlying physical data (which maycomprise one or more physical data representations 214). In this manner,a single application 140 may be used simultaneously by multiple users toaccess the same underlying data where the particular portions of theunderlying data exposed to the application are determined by therespective data repository abstraction component 148.

Any number of access methods are contemplated depending upon the numberof different types of logical fields to be supported. In one embodiment,access methods for simple fields, filtered fields and composed fieldsare provided. The field specifications 208 ₁, and 208 ₂ exemplify simplefield access methods 212 ₁, and 212 ₂, respectively. Simple fields aremapped directly to a particular entity in the underlying physical datarepresentation (e.g., a field mapped to a given database table andcolumn). By way of illustration, the simple field access method 212 ₁shown in FIG. 2B maps the logical field name 210 ₁ (“FirstName”) to acolumn named “f_name” in a table named “patient”. Filtered fields (noexample shown in FIG. 2) identify an associated physical entity andprovide rules used to define a particular subset of items within thephysical data representation. An example of a filtered field is a NewYork ZIP code field that maps to the physical representation of ZIPcodes and restricts the data only to those ZIP codes defined for thestate of New York. Composed access methods (e.g., 213 ₁, and 213 ₂,)compute a logical field from one or more physical fields using anexpression supplied as part of the access method definition. In thisway, information which does not exist in the underlying datarepresentation may computed. An example is a sales tax field that iscomposed by multiplying a sales price field by a sales tax rate.

It is contemplated that the formats for any given data type (e.g.,dates, decimal numbers, etc.) of the underlying data may vary.Accordingly, in one embodiment, the field specifications 208 include atype attribute which reflects the format of the underlying data.However, in another embodiment, the data format of the fieldspecifications 208 is different from the associated underlying physicaldata, in which case an access method is responsible for returning datain the proper format assumed by the requesting entity. Thus, the accessmethod must know what format of data is assumed (i.e., according to thelogical field) as well as the actual format of the underlying physicaldata. The access method can then convert the underlying physical datainto the format of the logical field.

By way of example, the field specifications 208 of the data repositoryabstraction component 148 shown in FIG. 2 are representative of logicalfields mapped to data represented in the relational data representation214 ₂. However, other instances of the data repository abstractioncomponent 148 map logical fields to other physical data representations,such as XML.

One or more of the field specifications 208 may also be configured witha correlation attribute (collectively depicted in FIG. 1 as correlationattributes 162). For example, the Diagnosis field specification 208 ₃includes an Age correlation attribute 218 ₁ and a Time correlationattribute 218 ₂, and the Test Result field specification 208 ₆ alsoincludes the Age correlation attribute 218 ₁ and the Time correlationattribute 218 ₂. It should be noted that not every field specificationneed have a correlation attribute.

Generally, the correlation attributes identify entities/events which alogical field may be correlated with respect to. In one embodiment,logical fields may be correlated with respect to time (a particularpoint in time or span of time), physical location and age. Thus, in oneembodiment, the correlation attributes identify the dimensions of spaceor time that may be used to constrain instances of data associated withthe logical field. However, more generally, correlation attributes couldbe defined that consider other properties of various entities involvedin query operations such as: color, weight, volume, length, width, etc.As can be seen from FIG. 2B, the correlation attributes associated witheach field definition generally comprise a “Name” and a “Fieldref”. TheName provides a handle for identifying the correlation attributeaccording to what the corresponding field (for which the correlationattribute is defined) can be correlated on. For example, the correlationattribute 218 ₁, is given the name “Age” signifying that thecorresponding logical field can be correlated with respect to age. Inthe present example, the Age correlation attribute 218 ₁ and the Timecorrelation attribute 218 ₂ are part of the field specifications for the“Diagnosis” logical field 210 ₃ and the “Test Result” logical field 210₆. The “Fieldref” provides the definition of the correlation attributefor a particular logical field. For example, the “Fieldref” for the Agecorrelation attribute 218 ₁ of the “Diagnosis” logical field 210 ₃specifies a definition referred to as “AgeAtDiagnosis”. In the presentembodiment, “AgeAtDiagnosis” is another logical field 210 ₅, which isalso part of the Diagnostics category 216 ₂. More specifically, the“AgeAtDiagnosis” logical field 210 ₅ is a composed field, as definedabove. In the present example, the composed logical field 210 ₅ receivesas input parameters the Diagnosis Date and Birth Date and takes thedifference between the parameter values. In this manner, the Agecorrelation attribute may take on any variety of definitions. Forexample, the Age correlation attribute 218 ₁ specified for the logicalfield Test Result 210 ₆ is defined according to the age at the test(Fieldref=“AgeAtTest”). The “AgeAtTest” logical field 210 ₈ is acomposed field receiving as input the Test Date and Birth Date andtaking the difference, whereby the age at the time of test iscalculated.

In operation, when an abstract query configured with correlationcriteria (such as the one illustrated in Table I and by the abstractquery 202 of FIG. 2B) is issued for execution, the correlation algorithm151 takes steps to determine whether each condition to which thecorrelation criteria are applied supports the correlation criteria. Thisis done using information in the corresponding data repositoryabstraction component 148 which defines the necessary metadata andaccess method information for logical fields that are referenced by theabstract query 202. Specifically, the correlation attributes 162 of thedata repository abstraction component 148 are examined to see whichcorrelation criteria are supported for the specified logical fields ofthe abstract query. For each logical field which supports thecorrelation criteria, additional predicates are added to an executablequery statement generated to represent the abstract query.

An illustrative data repository abstraction component 148 correspondingto that shown in FIG. 2B may be further illustrated with reference toTable II. By way of illustration, the Data Repository Abstractioncomponent is defined using XML. However, any other language may be usedto advantage.

TABLE II DATA REPOSITORY ABSTRACTION EXAMPLE 001 <DataRepository> 002 <Category name=”Demographic”> 003   <Field queryable=”Yes”displayable=”Yes” name=”FirstName”> 004    <AccessMethod> 005    <Simple columnName=”f_name” tableName=”patient” /> 006   </AccessMethod> 007    <Type baseType=”char”/> 008   </Field> 009  <Field queryable=”Yes” displayable=”Yes” name=”LastName”> 010   <AccessMethod> 011     <Simple columnName=”l_name”tableName=”patient” /> 012    </AccessMethod> 013    <TypebaseType=”char”/> 014   </Field> 015   <Field queryable=”Yes”displayable=”Yes” name=”BirthDate”> 016    <AccessMethod> 017    <Simple columnName=”b_date” tableName=”patient” /> 018   </AccessMethod> 019    <Type baseType=”date”/> 020   </Field> 021 </Category> 022  <Category name=”Diagnostics”> 023   <Fieldqueryable=”Yes” displayable=”Yes” name=”Diagnosis”> 024   <AccessMethod> 025     <Simple columnName=”diag” tableName=”patient”/> 026    </AccessMethod> 027    <Correlation name=”Age”fieldRef=”AgeAtDiagnosis”/> 028    <Correlation name=”Time”fieldRef=”DiagnosisDate”/> 029    <Type baseType=”char”/> 030   </Field>031   <Field queryable=”Yes” displayable=”Yes”     name=”DiagnosisDate”> 032    <AccessMethod> 033     <SimplecolumnName=”diagdate” tableName=”patient”/> 034    </AccessMethod> 035   <Type baseType=”date”/> 036   </Field> 037   <Field queryable=”Yes”displayable=”Yes”      name=”AgeAtDiagnosis”> 038    <AccessMethod> 039    <Composed> 040      <Composition>YEAR(Field(DiagnosisDate) −        Field(BirthDate)) 041       </Composition> 042     </Composed> 043   </AccessMethod> 044    <Type baseType=”int”/> 045   </Field> 046 </Category> 047  <Category name=”Tests”> 048   <Field queryable=”Yes”displayable=”Yes”      name=”Hemoglobin”> 049    <AccessMethod> 050    <Simple columnName=”testval” tableName=”patient” /> 051   </AccessMethod> 052    <Correlation name=”Age” fieldRef=”AgeAtTest”/>053    <Correlation name=”Time” fieldRef=”TestDate”/> 054    <TypebaseType=”int”/> 055   </Field> 056   <Field queryable=”Yes”displayable=”Yes” name=”TestDate”> 057    <AccessMethod> 058     <Simplecolumn Name=”testdate”        tableName=”patient” /> 059   </AccessMethod> 060    <Type baseType=”date”/> 061   </Field> 062  <Field queryable=”Yes” displayable=”Yes” name=”AgeAtTest”> 063   <AccessMethod> 064     <Composed> 065     <Composition>YEAR(Field(TestDate) −         Field(BirthDate)) 066     </Composition> 067     </Composed> 068    </AccessMethod> 069   <Type baseType=”int”/> 071   </Field> 072  </Category> 073</DataRepository>

One embodiment for processing abstract queries by the run-time component150 will now be described with reference to FIG. 3. The query processingmethod 300 is entered at step 302 where an abstract query is received bythe run-time component 150 for processing. Further, the runtimecomponent 150 reads and parses the instance of the abstract query andlocates individual selection criteria, correlation criteria and desiredresult fields. Add step 304, a loop is entered and performed for eachcorrelation criterion in the abstract query. Add step 306, the run-timecomponent 150 determines whether the criterion is a span type criterion,i.e., a criterion which correlates data entities based on the intervalof time between each data entity. For example, the abstract query shownin FIG. 2B includes the correlation criterion “Span (Time)<5” whichspecifies that the abstract query data entitles, for which the timecorrelation attribute applies, must be within five units of time(illustratively, days) of one another. If (at step 306) the criterion isa span type criterion, the criterion is added to a span criteria list170 (see also FIG. 1) at step 308. The method 300 then returns to step304 to begin processing for the next correlation criterion. If (at step306), the criterion is not a span type criterion, the criterion is addedto an individual criteria list 172 (see also FIG. 1) at step 310. Themethod 300 then returns to step 304 to begin processing for the nextcorrelation criterion.

Once each of the correlation criterions in the abstract query have beenprocessed, the method 300 continues to step 312 where a loop is enteredfor each condition having a selection criterion. Recall that, in oneembodiment, a condition may consist of a field name (for a logicalfield), a comparison operator (=, >, <, etc) and a value expression(what is the field being compared to). At step 314, the runtimecomponent 150 uses the field name from a condition of the abstract queryto look up the definition of the field in the data repositoryabstraction 148. The runtime component 150 then builds (step 316) anExecutable Query Contribution for the logical field being processed. Asdefined herein, an Executable Query Contribution is a portion of anexecutable query that is used to perform data selection based on thecurrent logical field. An executable query is a query represented inlanguages like SQL and XML Query and is consistent with the data of agiven physical data repository (e.g., a relational database or XMLrepository). Accordingly, the executable query is used to locate andretrieve data from the physical data repository, represented by thedatabase 156 shown in FIG. 1. The Executable Query Contributiongenerated for the current field is then added to an Executable QueryStatement, at step 318.

At step 320, the run-time component 150 determines whether the field ofthe condition being processed has a correlation attribute (i.e., in thedata repository abstraction component 148) corresponding to acorrelation criterion in the span criteria list 170. If so, the field isadded to a span field list 174 at step 322. In one embodiment, a spanfield list 174 is provided for each type of span correlation attribute(i.e., one list for Span(Time), another for Span(Location), etc).However, in another embodiment, a single span field list is created atthis step, a subset of fields is selected from this list when processingthe individual span correlation criteria (processing is describedbelow). The method 300 then returns to step 312 to begin processing thenext selection criterion condition. However, if step 320 is answerednegatively, processing continues to step 324 where the run-timecomponent 150 determines whether the field being processed has acorrelation attribute (i.e., in the data repository abstractioncomponent 148) corresponding to a correlation criterion in theindividual criteria list 172. If not, processing returns to step 312.Otherwise, the field definition of the correlation attribute for thefield being processed is retrieved from the data repository abstractioncomponent 148 at step 326. At step 328, the run-time component 150builds a query predicate from the correlation criterion and the fieldcorrelation attribute definition. The predicate is added to theexecutable query at step 330. Processing then returns to step 312.

When each of the selection criterion conditions have been processed bythe loop entered at step 312, the method 300 continues to step 332 wherea loop is entered for each pair of fields (i.e., non-order-dependentpermutation of fields for which the same correlation attribute isdefined) in the span field list 174. At step 334, the run-time component150 retrieves the field definition (i.e., from the data repositorydistraction component 148) of the correlation attribute for each fieldin the pair. At step 336, the run-time component 150 builds anexpression to compute the absolute difference between each fieldattribute definition (e.g., ABS(DAYS(testdate−diagdate))). Thisexpression is combined with the span criterion to form a span querypredicate involving the field pair (e.g.,ABS(DAYS(testdate−diagdate))>5). The predicate is then added to theexecutable query at step 340, and processing returns to step 332 for thenext pair of fields in the span field list 174. Once each pair of fieldshas been processed, the method 300 ends and the query is ready forexecution.

One embodiment of a method 400 for building an Executable QueryContribution for a logical field according to step 316 and step 328 isdescribed with reference to FIG. 4. At step 402, the method 400 querieswhether the access method associated with the current logical field is asimple access method. If so, the Executable Query Contribution is built(step 404) based on physical data location information and processingthen continues according to method 300 described above. Otherwise,processing continues to step 406 to query whether the access methodassociated with the current logical field is a filtered access method.If so, the Executable Query Contribution is built (step 408) based onphysical data location information for some physical data entity. Atstep 410, the Executable Query Contribution is extended with additionallogic (filter selection) used to subset data associated with thephysical data entity. Processing then continues according to method 300described above.

If the access method is not a filtered access method, processingproceeds from step 406 to step 412 where the method 400 queries whetherthe access method is a composed access method. If the access method is acomposed access method, the physical data location for each sub-fieldreference in the composed field expression is located and retrieved atstep 414. At step 416, the physical field location information of thecomposed field expression is substituted for the logical fieldreferences of the composed field expression, whereby the ExecutableQuery Contribution is generated. Processing then continues according tomethod 300 described above.

If the access method is not a composed access method, processingproceeds from step 412 to step 418. Step 418 is representative of anyother access methods types contemplated as embodiments of the presentinvention. However, it should be understood that embodiments arecontemplated in which less then all the available access methods areimplemented. For example, in a particular embodiment only simple accessmethods are used. In another embodiment, only simple access methods andfiltered access methods are used.

As noted earlier, the logical field referenced in the query conditionwill define the correlation attribute and a “FieldRef” that identifiesanother logical field which defines how to interpret the givencorrelation attribute for the query condition field. The method 400 ofFIG. 4 is executed using the “referenced” logical field and the logicassociated with the correlation attribute. For example, if correlationcriterion is Age >50 and a Test field includes a definition for Age witha FieldRef of AgeAtTest, then the method 400 builds a query predicatebased on the condition AgeAtTest >50.

As described above, it may be necessary to perform a data conversion ifa logical field specifies a data format different from the underlyingphysical data. In one embodiment, an initial conversion is performed foreach respective access method when building a Executable QueryContribution for a logical field according to the method 400. Forexample, the conversion may be performed as part of, or immediatelyfollowing, the steps 404, 408 and 416. A subsequent conversion from theformat of the physical data to the format of the logical field isperformed after the query is executed at step 322. Of course, if theformat of the logical field definition is the same as the underlyingphysical data, no conversion is necessary.

Foregoing examples are directed to the medical field and the correlationattributes are illustrated with respect to time, location and age.However, invention is not so limited and extension to any databaseenvironment and type of data is contemplated. For example, as mentionedabove, correlation attributes could be defined that consider otherproperties of various entities involved in query operations such as:color, weight, volume, length, width, etc. Consider the followingabstract query (TABLE III) for which a corresponding data abstractioncomponent may be defined.

TABLE III ABSTRACT QUERY EXAMPLE 001 <QueryAbstraction> 002  <Selection>003   <Condition field=”CarpetType” operator=”EQ” value=”berber”/> 004  <Condition field=”WallpaperPattern” operator=”EQ”      value=”floral”005 relOperator=”AND” /> 006  <Condition field=”PaintFinish”operator=”EQ” value=”satin” relOperator=”AND” 007 /> 008   <Correlationattribute=”Span(Color)” operator=”LT”      value=”10”/> 009 </Selection> 010  <Results> 011   <Field name=”CarpetNumber”/> 012  <Field name=”WallpaperNumber”/> 013   <Field name=”PaintNumber”/> 014 </Results> 015 </QueryAbstraction>

This abstract query is designed to select a set of carpet, wallpaper andcombinations based on criteria specified for type of carpet, pattern forthe wallpaper and type of paint finish. Assuming each entity here(carpet, wallpaper, paint) defined a correlation attribute of “color”,the correlation condition, Span(Color)<10, would restrict thecombinations selected to those that are similar in color. A possibledefinition for Span(Color) would be RGB values for color that werewithin “n” units of each other in Red, Green and Blue content.

Accordingly, the data repository abstraction component 148 providesvarious advantages. In one aspect, advantages are achieved by defining aloose coupling between the application query specification and theunderlying data representation. Rather than encoding an application withspecific table, column and relationship information, as is the casewhere SQL is used, the application defines data query requirements in amore abstract fashion that are then bound to a particular physical datarepresentation at runtime. The loose query-data coupling of the presentinvention enables requesting entities (e.g., applications) to functioneven if the underlying data representation is modified or if therequesting entity is to be used with a completely new physical datarepresentation than that used when the requesting entity was developed.In the case where a given physical data representation is modified orrestructured, the corresponding data repository abstraction is updatedto reflect changes made to the underlying physical data model. The sameset of logical fields are available for use by queries, and have merelybeen bound to different entities or locations in physical data model. Asa result, requesting entities written to the abstract query interfacecontinue to function unchanged, even though the corresponding physicaldata model has undergone significant change. In the event a requestingentity is to be used with a completely new physical data representationthan that used when the requesting entity was developed, the newphysical data model may be implemented using the same technology (e.g.,relational database) but following a different strategy for naming andorganizing information (e.g., a different schema). The new schema willcontain information that may be mapped to the set of logical fieldsrequired by the application using simple, filtered and composed fieldaccess method techniques. Alternatively, the new physical representationmay use an alternate technology for representing similar information(e.g., use of an XML based data repository versus a relational databasesystem). In either case, existing requesting entities written to use theabstract query interface can easily migrate to use the new physical datarepresentation with the provision of an alternate data repositoryabstraction which maps fields referenced in the query with the locationand physical representation in the new physical data model.

Further, the use of global correlation attributes together with anabstract query and underlying data abstraction model, greatly simplifiesthe task of describing complex data query logic involving a high degreeof data correlation and analysis. Furthermore, separation of the basedata selection logic from the correlation logic makes it possible toquickly reuse the same base query, but with different correlationconditions.

With regard to the end user, the data repository abstraction eliminatesmuch of the complexity associated with expressing correlated dataqueries. Specifically, the end-user no longer needs to worry about whichquery selection conditions support a given correlation approach, and isno longer burdened with having to understand how to express event-basedand/or entity-based (e.g., time-based, location-oriented, etc.) logicfor each new entity involved in a query.

While the use of a data repository abstraction model provides these andother advantages, it should be emphasized that persons skilled in theart will readily recognize that the purpose and function of thecorrelation attributes may be implemented separately from the datarepository abstraction component 148. For example, one embodimentprovides additional metadata to supplement information on tables andcolumns used by an SQL-based query implementation. In this case, themetadata for a given column would identify a correlation attribute suchas Age and an associated SQL query expression identifying how to computeage for the entity represented in the column. An SQL query pre-processorcould then take an initial SQL query and one or more correlationconditions as input and would augment the SQL query with additionalpredicates to account for the provided correlation conditions. Thiswould be done by scanning for references to the columns supporting thecorrelation attribute(s) from the set of correlation conditions andgenerating additional SQL WHERE clause predicates based on the queryexpression defined for a given column's definition of a particularcorrelation attribute.

It should be noted that any reference herein to particular values,definitions, programming languages and examples is merely for purposesof illustration. Accordingly, the invention is not limited by anyparticular illustrations and examples. Further, while aspects of theinvention are described with reference to SELECTION operations, otherinput/output operation are contemplated, including well-known operationssuch as ADD, MODIFY, INSERT, DELETE and the like. Of course, certainaccess methods may place restrictions on the type of abstract queryfunctions that can be defined using fields that utilize that particularaccess method. For example, fields involving composed access methods arenot viable targets of MODIFY, INSERT and DELETE.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A computer-implemented method of providing query attributes tofacilitate query composition, comprising: specifying a correlationattribute for one or more logical field definitions defined in a dataabstraction model that logically models physical data, each correlationattribute having a definition for determining a correspondingcorrelation condition; wherein each of the definitions comprise: alogical field name; at least one location attribute identifying alocation of physical data corresponding to the logical field name; and areference to an access method selected from at least two differentaccess method types, wherein each of the different access methods typesdefines a different manner of exposing the physical data correspondingto the logical field name of the respective logical field definition;wherein the correlation attributes, when present in an abstract queryreferencing one or more of the logical field definitions and one or morecorrelation attributes, configure a query processor to dynamically addquery logic to a query generated from the abstract query on the basis ofthe referenced correlation attributes and the corresponding logicalfields for which the correlation attributes are specified, the querylogic comprising the correlation conditions corresponding to thereferenced correlation attributes, whereby additional constraints areplaced on queries on the basis of user-specified query conditionswithout requiring user composition of the corresponding query logicdefining the additional constraints.
 2. The method of claim 1, whereinspecifying a correlation attribute for one or more logical fielddefinitions comprises specifying at least two different correlationattributes for at least one of the logical field definitions.
 3. Themethod of claim 1, wherein the value may be one of an age value, a timevalue and a location value.
 4. The method of claim 1, wherein the valuemay be one of a color value, a weight value, a volume value, a lengthvalue and a width value.
 5. A computer-implemented method of providingattributes configured to add query logic to queries generated fromabstract queries defined by one or more logical fields, the methodcomprising: providing a data abstraction model that logically describesphysical data and comprises a plurality of logical field definitions andone or more correlation attributes associated with at least some of theplurality of logical field definitions, wherein each of the logicalfield definitions comprise: a logical field name; at least one locationattribute identifying a location of physical data corresponding to thelogical field name; and a reference to an access method selected from atleast two different access method types; wherein each of the differentaccess methods types defines a different manner of exposing the physicaldata corresponding to the logical field name of the respective logicalfield definition; each correlation attribute having a definition fordetermining a corresponding correlation condition; and receiving anabstract query including (i) conditions referencing one or more of thelogical field definitions and (ii) one or more of the correlationattributes; generating an executable query from the abstract query, thegenerating comprising: determining whether the referenced correlationattributes are associated with any of the referenced logical fielddefinitions; and if so, applying, as part of the executable query, eachcorrelation condition corresponding to the respective referencedcorrelation attribute associated with the referenced logical fielddefinition.
 6. The method of claim 5, wherein at least one condition ofthe abstract query relates to an event having a corresponding time valuein the physical data and wherein at least one applied correlationcondition imposes a constraint on the condition on the basis of the timevalue.
 7. The method of claim 5, wherein at least one condition of theabstract query relates to an event having a corresponding value in thephysical data and wherein at least one applied correlation conditionsimposes a constraint on the condition on the basis of the value.
 8. Themethod of claim 7, wherein the value is a location value.
 9. The methodof claim 5, wherein at least one applied correlation condition is aparameterized condition that receives passed in values during the stepof applying.
 10. A computer-implemented method of adding query logic toqueries each having a plurality of conditions, the method comprising:receiving a query referencing one or more predefined correlationattributes, each correlation attribute having information defining apredicate with a predefined relationship to a given field, wherein thegiven field is a logical field defined in a logical field definition ina data abstraction model, and wherein generating query logic on thebasis of the predicate of the given field is done according to apredefined access method for the given field, the access method being amethod for accessing physical data corresponding to the given field,wherein the access method is referenced in the given field; for eachcorrelation attribute referenced in the query: (i) determining whetherthe query includes the given field for which the correlation attributehas the predefined relationship; and if so, (ii) generating query logicon the basis of the predicate of the given correlation attribute; andapplying the generated query logic to the query.
 11. The method of claim10, wherein the predicate imposes a time based constraint upon the givenfield.
 12. The method of claim 10, wherein the predicate is aparameterized condition that receives passed in values during thegenerating query logic.
 13. A computerized system, comprising: aprocessor; a memory containing a data structure containing a pluralityof correlation attributes each having information defining a predicatewith a predefined relationship to a given field, wherein the given fieldis a logical field defined in a logical field definition in a dataabstraction model and wherein generating query logic on the basis of thepredicate of the given field is done according to a predefined accessmethod for the given field, the access method being a method foraccessing physical data corresponding to the given field, wherein theaccess method is referenced in the given logical field and selected fromat least two different access method types; wherein each of thedifferent access method types defines a different manner of exposing thephysical data corresponding to a logical field name of the logical fielddefinition; a searchable data source containing a plurality of fields ofthe physical data, including those fields having predefinedrelationships with the predicates; and a query processor that, whenexecuted by the processor, is configured to: receive a query referencingone or more of the plurality of fields and one or more correlationattributes defined in the data structure; for each correlation attributereferenced in the query: (i) determine whether the query includes thegiven field for which the correlation attribute has the predefinedrelationship; and if so, (ii) generate query logic on the basis of thepredicate of the given correlation attribute; and apply the generatedquery logic to the query.
 14. The computerized system of claim 13,wherein the query processor is further configured to execute thegenerated query against the data source.
 15. The computerized system ofclaim 13, wherein the predicate is a parameterized condition thatreceives passed in values during the generating query logic.
 16. Thecomputerized system of claim 13, wherein the predicate imposes a timebased constraint upon the given field.